Finishing pad and method of making

ABSTRACT

A composite abrasive or finishing pad for use in sanding includes a sandpaper sheet having a paper based substrate having a front surface which has an abrasive grit adhered thereto and a back surface, a polyfoam backing reaction bonded to the back surface, wherein the polyfoam backing includes a first layer formed across the back surface of a first thickness sufficient enough to substantially aid in rendering the sandpaper tear-resistant and including a raised portion extending outward from the first layer a sufficient amount to form a wall portion against which lateral forces can be applied by one&#39;s fingers. A method of forming the pad is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel finishing pad and method of forming same. More particularly, the invention relates to a finishing pad and method of forming same employing a polyfoam material.

2. Related Art

Various abrasive sanding blocks structures exist in the field of sanding. Typically, these structures come in two forms, one in which conventional sandpaper is connected to a support block or device or another in which a sponge material is spray coated with abrasive grit. Still others have glued conventional abrasive sheets to a sponge.

Sponges have met with some success in that users find them easy to work with and hold. However, sponges have poor surfaces to which abrasive grits can be applied. U.S. Pat. No. 4,966,609 discloses a flexible abrasive article for cleaning, polishing or smoothing which includes foam with grit adhesively bonded to the foam.

Attempts to glue conventional sandpaper to porous foam has not resulted in a desirable product. For example, the product tends to be easily torn and worn out or peeled away from the foam. In order to provide a workable product, a fabric coated abrasive material is required for adhesive connection to foam. This increases expense and minimally enhances the product which can be obtained.

Sandpaper remains a more desirable product from a cost stand point. From a durability and performance standpoint, but the use of sandpaper as adhered to pads thus far has not been readily obtainable. A few attempts have been made to many the technologies. For example, U.S. patent application Ser. No. 11/404,451 shows a laminated abrasive article. The laminate shows an abrasive sheet glued to a backing sheet having continuous closed cell foam. U.S. patent application Ser. No. 11/683,064 shows a wet sanding sponge which includes a sponge having sandpaper sewn thereon.

Still other sanders have employed other ways to hold the sandpaper on a sander. These sanders typically employ wire clips or other clamping mechanisms to retain the sandpaper. Other sanders use hook and loop technology between a support structure and sandpaper. For example, the art has glued one hook/loop member to a rigid support structure and another hook/loop member to the sandpaper. These hook/loop members typically fail at the connection to the rigid support surface rendering the device useless. Sophisticated, expensive machines are required to control the coating of PSA's to abrasive articles. Additionally, suitable textiles for hook and loop-type fastening systems are generally expensive, especially when compared to pressure sensitive adhesives. Thus, adding textile materials to the back side of disposable abrasive articles increases their cost. Furthermore, adding textile materials to the back side of abrasive articles requires unique, sophisticated equipment.

Despite the improvements in the field, there is a continuous need to improve the sandpaper holding techniques, reduce costs on such sanders to ease the sanding process. There remains a need to improve composite structure for use in sanding. In co-pending application Ser. No. 12/110,477, there is disclosed one composite and method of making an improved abrasive composite. Even with these improvements, there remains a need to improve devices for hand sanding applications. The present invention improves the art of hand sanders currently existing in the marketplace. Accordingly, the present invention improves upon the art.

BRIEF SUMMARY OF THE INVENTION

It is an object to improve the method of making a composite abrasive.

It is another object to improve products by forming a composite abrasive.

Another object is to improve abrasive articles.

It is another object of the invention to provide an improved a composite abrasive structure for use in sanding.

It is a further object of the invention to provide a durable a composite abrasive structure for use in sanding.

Yet another object is to provide a multifaceted a hand-held composite abrasive tool.

It is an object of the invention to provide an improved finishing pad.

It is a further object of the present invention to provide a novel process for making high quality sandpaper having a unique polyfoam backing formed thereto.

Accordingly, the present invention is directed to a composite abrasive, or finishing pad, for use in sanding, which includes a sandpaper sheet having a paper based substrate having a front surface which has an abrasive grit adhered thereto and a back surface; a polyfoam backing reaction bonded to the back surface, wherein the polyfoam backing includes a first layer formed across the back surface of a first thickness sufficient enough to substantially aid in rendering the sandpaper tear-resistant and including a raised portion extending outward from the first layer a sufficient amount to form a wall portion against which lateral forces can be applied by one's fingers. Preferably, there is a plurality of wall portions which may be separate, continuous or contiguous and between which one's finger can be operably disposed such that upon lateral force being exerted by one's finger there is exerted a force on the wall portion and thereby provide a flexible and durable sandpaper sheet with an integral user friendly backing. The wall portions can include one or more curved or flat surfaces which can form ridges receiving one's fingers therebetween. It is noted that the walls or ridges are formed in a manner to enable the composite abrasive to remain flexible along valleys between the walls or ridges.

A method of forming the finishing pad or composite abrasive for use in sanding is provided. The method includes providing an openable/closable mold having a first surface which is generally flat and includes at least one orifice through which a negative pressure is enabled and a second surface having a which is generally of a first predetermined distance from the first surface of the mold when ready for forming the pad thereby providing a first forming area and wherein the second surface of the mold has at least one recessed surface thereby providing a second forming area, positionably disposing within an injection mold a sandpaper sheet having a front surface which includes an abrasive grit adhered thereto and a back surface, holding the sandpaper against a first surface of the injection mold via creating negative pressure through the orifice, and injecting polymer material into the mold in a manner such that a first portion of polyfoam is formed integrally connected to the back surface of the sandpaper via reaction bonding filling the first forming area and a second portion of polyfoam is formed filling the second forming area. Thus, upon formation, the mold is opened thereby permitting removal of the finishing pad with includes a sandpaper sheet having a paper based substrate having a front surface which has an abrasive grit adhered thereto and a back surface; a polyfoam backing reaction bonded to the back surface, wherein the polyfoam backing includes a first layer formed across the sandpaper back surface which is of a first thickness sufficient enough to substantially aid in rendering the sandpaper tear-resistant and including a raised portion extending outward from the first layer a sufficient amount to form a wall portion against which lateral forces can be applied by one's fingers.

Other objects and advantages will be readily apparent to those skilled in the art upon viewing the drawings and reading the detailed description hereafter. These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. A better understanding of the invention, its advantages, and objects obtained by its use, reference should be had to the drawings which form a further part hereof, and to the accompanying description, in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, in which like reference letters and numerals indicate corresponding parts throughout;

FIG. 1 is a view in perspective of an embodiment in accordance with the principles of the present invention;

FIG. 2 is a front view of FIG. 1;

FIG. 3 is an end view of FIG. 2;

FIG. 4 is a side view of FIG. 2;

FIG. 5 is a view in perspective of another embodiment of a finishing pad in accordance with the principles of the present invention;

FIG. 6 is a front view of FIG. 5;

FIG. 7 is a side view of FIG. 5; and

FIG. 8 is a side exploded view of FIG. 5;

FIG. 9 depicts cross section of a mold illustrating a method of making the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings of present invention, the finishing pad or composite abrasive is generally referred to by the numeral 10. The invention contemplates several variations to a continuous method of making the finishing pad or composite abrasive 10.

The invention uses a foaming material which can, for example, include polyol and isocyanate, which actively foams and expands in its mixed uncured state to form a cell foam core 12 when cured. The foaming material can be applied to a substrate in a manner as described herein wherein it is poured onto an abrasive sheet 14 coated with abrasive particles.

The composite abrasive or finishing pad 10 is for use in sanding or finishing. The sandpaper sheet 14 includes a paper based substrate having a front surface 16 which has an abrasive grit adhered thereto and a back surface 18. The polyfoam backing 12 can be reaction bonded to the back surface 18, wherein the polyfoam backing 12 includes a first layer 20 formed across the back surface 18 of a first thickness sufficient enough to substantially aid in rendering the sandpaper 14 tear-resistant. There is also provided one or more raised portions 22 extending outward from the first layer 20 a sufficient amount to form one or more wall portions 24 against which lateral forces can be applied by one's fingers. Preferably, there can be a plurality of wall portions 24 which may be separate, continuous or contiguous and between which one's finger can be operably disposed such that upon lateral force being exerted by one's finger there is exerted a force on the wall portion(s) 24. In the instant invention, several embodiments are seen in FIGS. 1-4 and 5-8 and 9. Note that the layer 20 is relatively thin to thereby provide a flexible pad 10 as well as lend durability to the sandpaper sheet 14. The raised portions 22 are so spaced and formed to provide the wall portions 24 in a manner which does not impede the overall flexibility of the pad 10 while enabling an integral user friendly backing. The wall portions 24 can include one or more curved or flat surfaces which can form ridges and valleys for receiving one's fingers. For example, the ridges and valleys enable the composite abrasive/pad 10 to remain flexible.

A method of forming the finishing pad/composite abrasive 10 for use in sanding is provided. The method includes providing an openable/closable mold 30 having a first surface 32 which is generally flat and includes at least one orifice 34, preferably several, through which a negative pressure is enabled and a second surface 36 having a which is generally of a first predetermined distance from the first surface 32 of the mold 30 when ready for forming the pad 10 thereby providing a first forming area 38 and wherein the second surface 36 of the mold 30 has at least one recessed surface 40 thereby providing a second forming area 42. The next step in the process is to positionably dispose within injection mold 30 sandpaper sheet 14 having front surface 16 with abrasive grit adhered thereto. While holding the sandpaper 14 against a first surface 32 of the injection mold 30 via creating negative pressure through the orifice 34 (e.g. with a vacuum), polymer material 12 is injected into the mold 30 in an active foaming and uncured state in a manner such that a first portion of polyfoam (layer 20) is formed integrally connected to the back surface 18 of the sandpaper 12 via reaction bonding filling the first forming area 38 and a second portion of is formed polyfoam (raised portion 22) filling the second forming area 42. Thus, upon formation, the mold 30 is opened thereby permitting removal of the finishing pad 10 with includes a sandpaper sheet 14 and a polyfoam backing reaction bonded to the back surface, wherein the polyfoam backing includes first layer formed 20 across the back surface 18 of a first thickness sufficient enough to substantially aid in rendering the sandpaper 14 tear-resistant while maintaining flexibility and including raised portion 22 extending outward from the first layer 20 a sufficient amount to form wall portion 24 against which lateral forces can be applied by one's fingers.

It is contemplated that the foaming material 14 components can be poured or sprayed into the mold 30. In the constrained rise process, the foaming material 12 which forms the core is applied from a bank of liquids in a metered continuous operation, commonly called the free rise process.

The formed pad 10 should be such as to provide comfortable flexibility. The abrasive sheet 14 can include a woven or non-woven material. A suitable temperature for curing the laminate is approximately 120 degree F., for example.

The composite abrasive/pad 10 shown is exemplary of that contemplated by the inventors and it is contemplated that there can be a design changes to facilitate a particular use of the pad 10. By so providing, the instant invention enables the manufacture of an improved composite abrasive/finishing pad 10 which offers desirable qualities in ease of use and durability than previously available in the market.

The above described embodiments are set forth by way of example and are not for the purpose of limiting the present invention. It will be readily apparent to those skilled in the art that obvious modifications, derivations and variations can be made to the embodiments without departing from the scope of the invention. Accordingly, the claims appended hereto should be read in their full scope including any such modifications, derivations and variations. 

1. A composite abrasive for use in sanding, which includes: a sandpaper sheet having a paper based substrate having a front surface with an abrasive grit adhered thereto and a back surface; and a polyfoam backing reaction bonded permanently to said back surface thereby forming a single composite polyfoam sandpaper sheet which after said abrasive grit's useful life is rendered to a state of non-reusability, wherein said polyfoam backing includes a layer formed across said back surface of a first thickness sufficient enough to substantially aid in rendering said sandpaper tear-resistant and to permit the sheet to maintain flexibility across said composite polyfoam sandpaper sheet and including a raised portion extending outward from the layer a sufficient amount to form a wall portion against which lateral forces can be applied by one's fingers.
 2. The composite abrasive of claim 1, which is further characterized to include a plurality of wall portions between which one's fingers can be operably disposed such that upon lateral force being exerted by one's finger there is exerted a force on said wall portion.
 3. The composite abrasive of claim 2, wherein said wall portions include one of a curved and flat surface forming ridge in a manner to enable said composite abrasive to remain flexible along valleys about said ridge.
 4. A finishing pad for use in sanding, which includes: a sandpaper sheet having a paper based substrate having a front surface with an abrasive grit adhered thereto and a back surface; and a polyfoam backing reaction bonded permanently to said back surface thereby forming a single composite polyfoam sandpaper sheet which after said abrasive grit's useful life is rendered to a state of non-reusability, wherein said polyfoam backing includes a layer formed across said back surface of a first thickness sufficient enough to substantially aid in rendering said sandpaper tear-resistant and to permit the sheet to maintain flexibility across said composite polyfoam sandpaper sheet and including a raised portion extending outward from the layer a sufficient amount to form a wall portion against which lateral forces can be applied by one's fingers.
 5. The finishing pad of claim 4, which is further characterized to include a plurality of wall portions between which one's finger can be operably disposed such that upon lateral force being exerted by one's finger there is exerted a force on said wall portion.
 6. The finishing pad of claim 5, wherein said wall portions include one of a curved and flat surface forming ridge in a manner to enable said finishing pad to remain flexible along valleys about said ridge.
 7. (canceled) 